When viewing extended objects, the apparent brightness seen in the eyepiece is a function only of aperture and magnification, it is not related to focal ratio.
当观察扩展光源时，目镜中所看到的亮度只跟孔径和放大率有关，它跟焦比并没有关系。
If you know the focal ratio but not the focal length, you can calculate it: focal length is the aperture (in mm) times the focal ratio.
如果你不知道焦距，只知道焦比(focalratio)，你可以通过这样计算的得到焦距：孔径(单位是mm)乘以焦比就是焦距。
For example, the focal length of an 8" (203.2mm) aperture with a focal ratio of f/10 would be 203.2 x 10 = 2032mm.
比如，孔径为8英寸(203.2mm)，焦比为f/10的透镜，其焦距为203.2x 10 = 2032mm。
This is the ratio of the focal length of the telescope to its aperture.
这是指望远镜的焦距与其孔径的比值。
This paper discusses the backscattering by a target placed in the focal plane of a focused aperture.
研究了目标在聚焦口径天线焦点的散射问题。
FLIR – The large aperture enables a longer focal length, which provides higher resolution without losing sensitivity.
大孔径允许更长的焦距，从而在不损失灵敏度的情况下，提供更高的分辨率。
From the theory of light diffraction and geometrical optics, aperture diffraction near the focal plane of microscope objectives and imaging on the image plane are studied.
从光的衍射理论和几何成象理论出发，分析研究了显微物镜焦平面附近小孔光栏的衍射和象平面位置上的成象。
The quantity in relation to the coupling efficiency of an optical fiber:lasing mode, divergence angle, numerical aperture, focal diameter and precision optical fiber coupler are discussed.
围绕光纤耦合效率相关的量：激光模式、发散角、数值孔径、焦斑直径、精密光纤耦合器等问题进行了讨论；
The basic factors affecting collimating characteristic are off-axis magnitude, effective aperture and emission position on the focal plane of off-axis parabolic mirror.
影响离轴抛物镜准直特性的主要因素有离轴量，有效孔径和焦面出射点的位置。
Thermal imaging systems based on uncooled focal plane array detectors require their optical lens with a large relative aperture.
基于非致冷焦平面阵列探测器的热成像系统，要求光学系统具有足够大的相对孔径。
A method is introduced for testing stray light coefficient, vignetting coefficient and image surface uniformity optical system with large aperture and long focal length.
叙述一种用于测试大口径、长焦距光学系统杂光系数、渐晕系数、像面照度均匀性等光学参数的检测方法。
When a target is placed in the focal plane of a focused aperture antenna, the backscattered power from the target may be greatly enhanced by properly choosing the aperture distribution.
当目标处于聚焦天线焦平面上时，可通过选择口径分布来提高目标的后向散射功率。
For large aperture lens, scanning method was developed to measure the focal length in different locations within the mirror.
针对被测镜大口径的问题，采用了扫描的方法，这样可以测量被测镜不同位置的焦距。
But only with the right focal distance and correct aperture could we get the true pictures.
只有我们调对了焦距，对准了光圈，才有可能得到真实的图像。
The sizes of focal spot and detector aperture are the factors affecting ct image quality.
射线源焦点及探测器孔径大小是导致CT图象降质的主要因素。
When the aperture diameter of an optical system is fixed with the same orbit height, the resolution of ground objects can be improved by increasing the focal length.
当光学系统口径一定时，在相同的轨道高度条件下，增大焦距可以提高地面分辨率，增大系统的视场角可以扩大对地面的覆盖宽度。
When the diffractive optical lens is illuminated by white light, its focal length not only relates to material dispersion and wavelength dispersion, but also to aperture factor.
在白光照射下，衍射光学透镜的焦距不仅同材料色散和波长色散有关，而且还同孔径因子有关。
Through the system optimization, the analysis of aberration and differential thermal, the designed system is simple, light weight, large aperture, long focal, and good temperature adaptability.
该系统具有结构简单、质量轻、口径大、焦距长、失真小以及良好温度适应性等特点。
It investigates the focal switch phenomenon of a tilted phase L-G beam passing through a system with the aperture and lens separated.
研究了相位倾斜l - G光束通过光阑——透镜分离系统的焦开关现象。
This works for all apertures and focal lengths, but the smaller the aperture and the shorter the focal length, and the greater the distance you shoot at, the greater the depth of field.
这在任何光圈和焦距上都适用，只不过光圈越小、焦距越短，景深越大，你能够拍摄的清晰长度就越大。
Therefore the adjustment of the focal length and the aperture of the optical system have direct influence on the imaging quality.
因此光学系统焦距、光圈的调节直接影响系统的成像质量。
The aperture size (area of the aperture) of a lens could be calculated from focal length and the correspondent f-number.
光圈孔的大小，可从镜头的焦距与焦距比数中计算出来。
But, if you plan to share your images on a photo hosting site and would like to indicate the focal length, aperture and other parameters to your viewers, Save for Web will not be the right method.
但是，如果你想要在网络相册中分享你的照片，并且希望观看者看到拍摄的焦距、光圈和其它参数，那么就不适合使用另存为网页格式了。
It is proved that a small circular aperture has the positive and minus focal distances, and the research experiments for small aperture glasses are introduced concisely.
提出了证明小圆孔具有正、负焦距的一种方法，简要地介绍了关于小孔眼镜的实验研究。
It is proved that a small circular aperture has the positive and minus focal distances, and the research experiments for small aperture glasses are introduced concisely.
提出了证明小圆孔具有正、负焦距的一种方法，简要地介绍了关于小孔眼镜的实验研究。
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